This repo implements the Fillet and Chamfer function for inkscape described as http://launchpadlibrarian.net/12692602/rcp.svg. svgpathtools library is required.
pip install svgpathtools --user
cp filletchamfer.inx ~/.config/inkscape/extensions/
cp filletchamfer.py ~/.config/inkscape/extensions/
The extension can be accessed form Extensions -> Generate from Path -> Fillet and Chamfer.